This invention relates to puffer type circuit interrupters, and more specifically relates to a novel arcing contact configuration for puffer interrupters in which flexible finger contacts are contained adjacent the upstream surface of the nozzle of the puffer breaker and slidably engage a stationary contact tube which projects into the nozzle orifice when the breaker is closed.
Puffer type interrupters are well known in the art and generally consist of a pair of relatively movable contacts where one of the contacts is connected, for example, to a cylinder which moves over a stationary piston so that a blast of gas is produced when the contacts are opened. A nozzle is also connected to the movable contact to direct the gas blast in the most efficient manner to obtain cooling and interruption of the arc drawn between the separating contacts.
In contact arrangements which have been used in the prior art, the contacts conventionally engage one another at a point slightly upstream of an orifice restriction within the nozzle. When the contacts begin to move to an open position relative to one another, the prior art designs have permittted gas leakage during precompression of the volume between the contact fingers of the stationary arcing contact so that there is some pressure loss at the early part of the contact stroke. Moreover, prior art arrangements require a relatively large nozzle diameter when the stationary contact is designed as a finger contact which engages and encloses a stationary arcing contact positioned within the nozzle.
In order to avoid this problem, some arrangements in the prior art have made the contact member within the nozzle a finger type contact which engages a relatively small diameter tubular contact, thus permitting the use of a relatively small nozzle orifice. Devices of this type, however, have the disadvantage of a long upstream arc length and, moreover, the arc root on the contact within the nozzle is at a position which is not easily cooled by the flow of gas within the nozzle.